The invention relates to a device and a method for the thermal bonding of a textile web, whereby the textile web is guided over an idler drum in a bonding plant, then round a through-air drum and over a cooling drum before being guided out again.
In these thermal bonding plants, nonwovens made from or with thermoplastic fibers are heat set or bonded by means of hot air, saturated steam or hot water in order to reduce stresses in the web and fix the fibers. In this, warmed-up air is fed to a processing space, whereby the fresh air is led through the web into a through-air drum and then extracted via a fan. The fresh air absorbs the moisture from the web and heats this. A negative pressure is created within the bonding plant which, in combination with the air streams, forms different pressure and flow conditions. With the negative pressure, high temperature and loss of moisture, the web tends to adhere to the drum resulting in the operating speed having to be reduced and resulting in damage to the web. The adhering to the drum can be quite strong with certain products, e.g. those containing bicomponent fibers.
A circulating air dryer is described in WO2012/055732A1 with which the air permeability of the screen cover arranged in the housing can be set.
The circulating air dryer of WO2012/127013 manifested an extraction device arranged in the drum with which hot air is sucked from the processing space and through the material web using a large negative pressure.
In DE 102009016019 A1, a circulating air dryer is coupled to a heat exchanger whereby the heat exchanger warms up fresh air and this warmed air is led to the processing space.
DE 102007053030 A1 describes a circulating air dryer in which the web to be dried is led around an air-permeable drum in a housing and redirected by and pulled off a cooling drum. The air from the cooling drum can then get into the drum and mix there with the warm air—which is not efficient.